Here is my take on this, fully prefaced with "I am not a lawyer" and "I am not an insider in this case" (aka I'm a certified "keyboard expert"):
1) The waiver is barely worth the paper it is written on, you can't sign away the right to sue someone else for their negligence. All of the waivers and things in the rulebook provide merely speed bumps to competent attorneys, sadly.
2) As I understand it, the car was up to spec at the time it was built and raced. The rules regarding driveshaft protection were put in as a result of this incident, not before it.
3) My guess is that her lawyers will argue that the defendants (NMCA, NHRA, the race car manufacturer, the poor tech guy) should have known she was at risk, based upon previous incidents, or some such. This would constitute negligence, and would be the basis for the suit.
This is all so sad. She was maimed, and that has to be terrible. But virtually every line in the rulebook was created as the result of someone's misfortune. Things people didn't expect to see happened, and measures were taken to prevent them from happening again. In fact, that's what happened in this case: rules were quickly put in place to prevent a recurrence. The vast majority of people for whom these terrible things happened were satisfied with the knowledge that steps were taken to prevent them from happening to others.
Unfortunately, in this case, the poor victim has been convinced by some hot-shot attorney that there is also free money to be had. "This will never go to court, the insurance companies will settle, no one will get hurt, not the NHRA, not the tech guy. Only the big insurance companies will get hurt, and it means free money for you. With all your pain, don't you deserve that?"
As I said, it's so sad. Because in point of fact, we will all pay. Both in higher premiums and in fewer and fewer companies willingness to participate (both as insurers and as suppliers) in the sport we love.